Bodily Oddities

Joint hypermobility

Also called: Double-jointedness · Generalised joint hypermobility · Hypermobility spectrum disorder

About 1 in 5 people have joints that bend further than usual, measured with a nine-point test called the Beighton score. For most people it causes no trouble.

Bones and joints Whole body Variation Structural
Try it Get it checked Genetic Party trick

How common

10–25% of people Common · 10–50% About 3% have hypermobility with pain or other symptoms. More common in women, in children, and in some ethnic groups.

Do you have this?

These are answers from visitors, not a study.

How it works

Nobody has double joints. The word describes joints that move further than average1. In hypermobile people the ligaments are more elastic than usual. This comes from the collagen proteins that make up the ligaments, and it runs in families1.

The standard test is the Beighton score2. It has nine points, one for each of these checks:

  • Bending each little finger back past 90 degrees (one point per hand).
  • Bending each thumb back to touch the forearm (one point per hand).
  • Straightening each elbow more than 10 degrees past straight (one point per arm).
  • Straightening each knee more than 10 degrees past straight (one point per leg).
  • Placing both palms flat on the floor with straight knees (one point).

A score of 5 or more out of 9 is usually counted as hypermobile in adults2. Some doctors use 6 for children and 4 for people over 50, because flexibility falls with age2.

Between 10% and 25% of people score as hypermobile1. Most of them have no symptoms. About 3% have joint pain, frequent sprains, or dislocations along with the flexibility1. Doctors call that hypermobility spectrum disorder.

Try it

These are three of the nine Beighton checks2.

  1. Hold one hand flat, palm down. With the other hand, bend the little finger straight back. If it passes 90 degrees, that is one point.
  2. Bend your thumb down toward the inside of your forearm. If the thumb touches the forearm, that is one point.
  3. Stand with your knees straight and bend forward. If both palms rest flat on the floor, that is one point.
  4. Repeat steps 1 and 2 on the other hand. Add the points. Five or more suggests hypermobility.

Is it a problem?

For most people, no. Flexible joints are normal and are useful in dance, gymnastics, and music. See a doctor if many joints are loose and you also have regular pain, joints that slip out of place, very stretchy or fragile skin, or frequent unexplained bruising. These can point to a connective tissue condition such as Ehlers-Danlos syndrome, which needs a proper assessment3.

History and culture

Contortionists are usually hypermobile and train it further. Groups such as r/ehlersdanlos share advice on living with the symptomatic form4.

Sources and further material

  1. Encyclopedia Hypermobility (joints)
  2. Encyclopedia Beighton score
  3. Encyclopedia Ehlers-Danlos syndromes
  4. Community r/ehlersdanlos Community for people with the symptomatic connective tissue form.
Bones Trick

Voluntary joint dislocation

Pushing a joint partly or fully out of its socket on purpose, then back in. About 20% of people have some joint hypermobility. True voluntary dislocation is much rarer and often linked to a connective tissue disorder.

Rare; no formal count Icky
Bones Trick

Knuckle cracking

Pulling or bending a finger joint until it pops. Between 25% and 54% of people do it out of habit. The sound is a gas bubble forming in the joint fluid, and it does not cause arthritis.

25–54% crack habitually
Mouth Trick

Gorlin's sign

Touching the tip of your nose with your tongue. About 10% of people can do it. About half of people with Ehlers-Danlos syndrome can, so doctors use it as a quick check for stretchy connective tissue.

~10% of people
Bones Variation

Hitchhiker's thumb

A thumb whose top joint bends back past 50 degrees, once taught as a simple recessive gene. Thumb angle is really a smooth range, and the genetics are not that simple.

24–36% of people